1To make the chocolate simple syrup, combine half a cup of water and half a cup of granulated sugar in a saucepan and heat until the sugar is fully dissolved.
2Mix in one tablespoon of dark cocoa powder into the simple syrup.
3Pour the chocolate simple syrup into a jar and let it cool.
4Whisk together all the dry ingredients: two cups of all-purpose flour, two cups of granulated sugar, three-quarters of a cup of dark cocoa powder, two teaspoons of baking powder, one and a half teaspoons of baking soda, and one teaspoon of fine salt.
5Combine the wet ingredients: one cup of warm water, one cup of sour cream, half a cup of vegetable oil, two large eggs, two teaspoons of vanilla extract, and one teaspoon of instant espresso.
6Whisk the wet ingredients until thoroughly combined.
7Pour the wet ingredients into the dry ingredients.
8Whisk the mixture together until smooth to create the cake batter.
9Line and grease your cake pans.
10Pour the cake batter into the prepared cake pans; this recipe yields three 8-inch cake layers or two 9-inch cake layers.
11Bake the cake layers at 350 degrees Fahrenheit for 22 to 26 minutes.
12For the chocolate frosting, mix together two cups of unsalted butter, one cup of dark baking cocoa, one teaspoon of vanilla extract, and half a teaspoon of salt.
13Mix in five cups of powdered sugar and three-quarters of a cup of heavy cream on a low speed.
14Mix in one and a third cups of melted and cooled dark chocolate.
15Brush the cake layers with the cooled chocolate simple syrup.
16Spread an even layer of the chocolate frosting onto the first cake layer.
17Place the next cake layer on top and repeat the brushing with syrup and spreading of frosting.
18Add a final thick layer of chocolate buttercream to the top and sides of the cake, omitting a crumb coat for simplicity.
19Decorate the cake with extra cake crumbs if desired; this step is optional.